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Sanidas I, Lawrence MS, Dyson NJ. Patterns in the tapestry of chromatin-bound RB. Trends Cell Biol 2024; 34:288-298. [PMID: 37648594 PMCID: PMC10899529 DOI: 10.1016/j.tcb.2023.07.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2023] [Revised: 07/27/2023] [Accepted: 07/28/2023] [Indexed: 09/01/2023]
Abstract
The retinoblastoma protein (RB)-mediated regulation of E2F is a component of a highly conserved cell cycle machine. However, RB's tumor suppressor activity, like RB's requirement in animal development, is tissue-specific, context-specific, and sometimes appears uncoupled from cell proliferation. Detailed new information about RB's genomic distribution provides a new perspective on the complexity of RB function, suggesting that some of its functional specificity results from context-specific RB association with chromatin. Here we summarize recent evidence showing that RB targets different types of chromatin regulatory elements at different cell cycle stages. RB controls traditional RB/E2F targets prior to S-phase, but, when cells proliferate, RB redistributes to cell type-specific chromatin loci. We discuss the broad implications of the new data for RB research.
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Affiliation(s)
- Ioannis Sanidas
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA
| | - Michael S Lawrence
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA; Broad Institute of MIT and Harvard, 415 Main Street, Cambridge, MA 02142, USA
| | - Nicholas J Dyson
- Massachusetts General Hospital Cancer Center and Harvard Medical School, Building 149, 13th Street, Charlestown, MA 02129, USA.
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2
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Rani N, Sahu M, Ambasta RK, Kumar P. Triaging between post-translational modification of cell cycle regulators and their therapeutics in neurodegenerative diseases. Ageing Res Rev 2024; 94:102174. [PMID: 38135008 DOI: 10.1016/j.arr.2023.102174] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2023] [Revised: 12/18/2023] [Accepted: 12/18/2023] [Indexed: 12/24/2023]
Abstract
Neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and Huntington's disease, present challenges in healthcare because of their complicated etiologies and absence of healing remedies. Lately, the emerging role of post-translational modifications (PTMs), in the context of cell cycle regulators, has garnered big interest as a potential avenue for therapeutic intervention. The review explores the problematic panorama of PTMs on cell cycle regulators and their implications in neurodegenerative diseases. We delve into the dynamic phosphorylation, acetylation, ubiquitination, SUMOylation, Glycation, and Neddylation that modulate the key cell cycle regulators, consisting of cyclins, cyclin-dependent kinases (CDKs), and their inhibitors. The dysregulation of these PTMs is related to aberrant cell cycle in neurons, which is one of the factors involved in neurodegenerative pathologies. Moreover, the effect of exogenous activation of CDKs and CDK inhibitors through PTMs on the signaling cascade was studied in postmitotic conditions of NDDs. Furthermore, the therapeutic implications of CDK inhibitors and associated alteration in PTMs were discussed. Lastly, we explored the putative mechanism of PTMs to restore normal neuronal function that might reverse NDDs.
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Affiliation(s)
- Neetu Rani
- Molecular Neuroscience and Functional Genomics Laboratory, Department of Biotechnology, Delhi Technological University (Formerly DCE), Delhi 110042
| | - Mehar Sahu
- Molecular Neuroscience and Functional Genomics Laboratory, Department of Biotechnology, Delhi Technological University (Formerly DCE), Delhi 110042
| | - Rashmi K Ambasta
- Molecular Neuroscience and Functional Genomics Laboratory, Department of Biotechnology, Delhi Technological University (Formerly DCE), Delhi 110042; Department of Biotechnology and Microbiology, SRM University, Sonepat, Haryana, India.
| | - Pravir Kumar
- Molecular Neuroscience and Functional Genomics Laboratory, Department of Biotechnology, Delhi Technological University (Formerly DCE), Delhi 110042.
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3
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Kim S, Jo S, Paek SH, Kang SS, Chung H. SUZ12 inhibition attenuates cell proliferation of glioblastoma via post-translational regulation of CDKN1B. Genes Genomics 2023; 45:1623-1632. [PMID: 37856053 DOI: 10.1007/s13258-023-01468-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Accepted: 10/10/2023] [Indexed: 10/20/2023]
Abstract
BACKGROUND Human gliomas are aggressive brain tumors characterized by uncontrolled cell proliferation. Differential expression of Polycomb repressive complex 2 (PRC2) has been reported in various subtypes of glioma. However, the role of PRC2 in uncontrolled growth in glioma and its underlying molecular mechanisms remain to be elucidated. OBJECTIVE We aimed to investigate the functional role of PRC2 in human glioblastoma cell growth by silencing SUZ12, the non-catalytic core component of PRC2. METHODS Knockdown of SUZ12 was achieved by infecting T98G cells with lentivirus carrying sequences specifically targeting SUZ12 (shSUZ12). Gene expression was examined by quantitative PCR and western analysis. The impact of shSUZ12 on cell growth was assessed using a cell proliferation assay. Cell cycle distribution was analyzed by flow cytometry, and protein stability was evaluated in cycloheximide-treated cells. Subcellular localization was examined through immunofluorescence staining and biochemical cytoplasmic-nuclear fractionation. Gene expression analysis was also performed on human specimens from normal brain and glioblastoma patients. RESULTS SUZ12 knockdown (SUZ12 KD) led to widespread decrease in the PRC2-specific histone mark, accompanied by a slowdown of cell proliferation through G1 arrest. In SUZ12 KD cells, the degradation of CDKN1B protein was reduced, resulting from alterations in the MYC-SKP2-CDKN1B axis. Furthermore, nuclear localization of CDKN1B was enhanced in SUZ12 KD cells. Analysis of human glioblastoma samples yielded increased expression of EZH2 and MYC along with reduced CDKN1B compared to normal human brain tissue. CONCLUSION Our findings suggest a novel role for SUZ12 in cell proliferation through post-translational regulation of CDKN1B in glioblastoma.
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Affiliation(s)
- Sojin Kim
- Department of Biomedical Laboratory Science, Daegu Health College, Daegu, 41453, Republic of Korea
| | - Sungsin Jo
- Hanyang University Institute for Rheumatology Research (HYIRR), Seoul, 04763, Republic of Korea
| | - Sun Ha Paek
- Department of Neurosurgery, Seoul National University College of Medicine, Seoul National University Hospital, Seoul, 03080, Republic of Korea
| | - Sang Soo Kang
- Department of Anatomy and Convergence Medical Science, Gyeongsang National University, Jinju, 52727, Republic of Korea
| | - Heekyoung Chung
- Hanyang Biomedical Research Institute, Hanyang University, Seoul, 04763, Republic of Korea.
- Department of Pathology, Hanyang University, Seoul, 04763, Republic of Korea.
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Bai L, Li X, Yang Y, Zhao R, White EZ, Danaher A, Bowen NJ, Hinton CV, Cook N, Li D, Wu AY, Qui M, Du Y, Fu H, Kucuk O, Wu D. Bromocriptine monotherapy overcomes prostate cancer chemoresistance in preclinical models. Transl Oncol 2023; 34:101707. [PMID: 37271121 PMCID: PMC10248552 DOI: 10.1016/j.tranon.2023.101707] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2023] [Revised: 05/12/2023] [Accepted: 05/29/2023] [Indexed: 06/06/2023] Open
Abstract
Chemoresistance is a major obstacle in the clinical management of metastatic, castration-resistant prostate cancer (PCa). It is imperative to develop novel strategies to overcome chemoresistance and improve clinical outcomes in patients who have failed chemotherapy. Using a two-tier phenotypic screening platform, we identified bromocriptine mesylate as a potent and selective inhibitor of chemoresistant PCa cells. Bromocriptine effectively induced cell cycle arrest and activated apoptosis in chemoresistant PCa cells but not in chemoresponsive PCa cells. RNA-seq analyses revealed that bromocriptine affected a subset of genes implicated in the regulation of the cell cycle, DNA repair, and cell death. Interestingly, approximately one-third (50/157) of the differentially expressed genes affected by bromocriptine overlapped with known p53-p21- retinoblastoma protein (RB) target genes. At the protein level, bromocriptine increased the expression of dopamine D2 receptor (DRD2) and affected several classical and non-classical dopamine receptor signal pathways in chemoresistant PCa cells, including adenosine monophosphate-activated protein kinase (AMPK), p38 mitogen-activated protein kinase (p38 MAPK), nuclear factor kappa B (NF-κB), enhancer of zeste homolog 2 (EZH2), and survivin. As a monotherapy, bromocriptine treatment at 15 mg/kg, three times per week, via the intraperitoneal route significantly inhibited the skeletal growth of chemoresistant C4-2B-TaxR xenografts in athymic nude mice. In summary, these results provided the first preclinical evidence that bromocriptine is a selective and effective inhibitor of chemoresistant PCa. Due to its favorable clinical safety profiles, bromocriptine could be rapidly tested in PCa patients and repurposed as a novel subtype-specific treatment to overcome chemoresistance.
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Affiliation(s)
- Lijuan Bai
- Department of Geriatrics, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei, China
- Molecular Oncology and Biomarkers Program, Georgia Cancer Center; Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA, USA
| | - Xin Li
- Molecular Oncology and Biomarkers Program, Georgia Cancer Center; Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA, USA
- Center for Cancer Research and Therapeutic Development and Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, USA
| | - Yang Yang
- Molecular Oncology and Biomarkers Program, Georgia Cancer Center; Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA, USA
- Department of Otorhinolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Rui Zhao
- Molecular Oncology and Biomarkers Program, Georgia Cancer Center; Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA, USA
- Department of Urology, China-Japan Union Hospital of Jilin University, Changchun, Jilin, China
| | - Elshaddai Z. White
- Center for Cancer Research and Therapeutic Development and Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, USA
| | - Alira Danaher
- Center for Cancer Research and Therapeutic Development and Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, USA
| | - Nathan J. Bowen
- Center for Cancer Research and Therapeutic Development and Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, USA
| | - Cimona V. Hinton
- Center for Cancer Research and Therapeutic Development and Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, USA
| | - Nicholas Cook
- Center for Cancer Research and Therapeutic Development and Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, USA
| | - Dehong Li
- Center for Cancer Research and Therapeutic Development and Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, USA
| | - Alyssa Y. Wu
- Emory College of Arts and Sciences, Atlanta, GA, USA
| | - Min Qui
- Department of Pharmacology and Chemical Biology, and Emory Chemical Biology Discovery Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Yuhong Du
- Department of Pharmacology and Chemical Biology, and Emory Chemical Biology Discovery Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Haian Fu
- Department of Pharmacology and Chemical Biology, and Emory Chemical Biology Discovery Center, Emory University School of Medicine, Atlanta, GA, USA
| | - Omer Kucuk
- Department of Hematology and Medical Oncology, Winship Cancer Institute, Emory University School of Medicine, Atlanta, GA, USA
- Department of Urology, Emory University School of Medicine, Atlanta, GA, USA
| | - Daqing Wu
- Molecular Oncology and Biomarkers Program, Georgia Cancer Center; Department of Biochemistry and Molecular Biology, Medical College of Georgia, Augusta University, Augusta, GA, USA
- Center for Cancer Research and Therapeutic Development and Department of Biological Sciences, Clark Atlanta University, Atlanta, GA, USA
- Department of Urology, Emory University School of Medicine, Atlanta, GA, USA
- MetCure Therapeutics LLC, Atlanta, GA, USA
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5
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He W, Demas DM, Shajahan-Haq AN, Baumann WT. Modeling breast cancer proliferation, drug synergies, and alternating therapies. iScience 2023; 26:106714. [PMID: 37234088 PMCID: PMC10206440 DOI: 10.1016/j.isci.2023.106714] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2022] [Revised: 02/12/2023] [Accepted: 04/18/2023] [Indexed: 05/27/2023] Open
Abstract
Estrogen receptor positive (ER+) breast cancer is responsive to a number of targeted therapies used clinically. Unfortunately, the continuous application of targeted therapy often results in resistance, driving the consideration of combination and alternating therapies. Toward this end, we developed a mathematical model that can simulate various mono, combination, and alternating therapies for ER + breast cancer cells at different doses over long time scales. The model is used to look for optimal drug combinations and predicts a significant synergism between Cdk4/6 inhibitors in combination with the anti-estrogen fulvestrant, which may help explain the clinical success of adding Cdk4/6 inhibitors to anti-estrogen therapy. Furthermore, the model is used to optimize an alternating treatment protocol so it works as well as monotherapy while using less total drug dose.
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Affiliation(s)
- Wei He
- Program in Genetics, Bioinformatics, and Computational Biology, VT BIOTRANS, Virginia Tech, Blacksburg, VA 24061, USA
| | - Diane M. Demas
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
| | - Ayesha N. Shajahan-Haq
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC 20057, USA
| | - William T. Baumann
- Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, VA 24061, USA
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6
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Proteogenomic analysis of lung adenocarcinoma reveals tumor heterogeneity, survival determinants, and therapeutically relevant pathways. Cell Rep Med 2022; 3:100819. [PMID: 36384096 PMCID: PMC9729884 DOI: 10.1016/j.xcrm.2022.100819] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Revised: 05/09/2022] [Accepted: 10/18/2022] [Indexed: 11/17/2022]
Abstract
We present a deep proteogenomic profiling study of 87 lung adenocarcinoma (LUAD) tumors from the United States, integrating whole-genome sequencing, transcriptome sequencing, proteomics and phosphoproteomics by mass spectrometry, and reverse-phase protein arrays. We identify three subtypes from somatic genome signature analysis, including a transition-high subtype enriched with never smokers, a transversion-high subtype enriched with current smokers, and a structurally altered subtype enriched with former smokers, TP53 alterations, and genome-wide structural alterations. We show that within-tumor correlations of RNA and protein expression associate with tumor purity and immune cell profiles. We detect and independently validate expression signatures of RNA and protein that predict patient survival. Additionally, among co-measured genes, we found that protein expression is more often associated with patient survival than RNA. Finally, integrative analysis characterizes three expression subtypes with divergent mutations, proteomic regulatory networks, and therapeutic vulnerabilities. This proteogenomic characterization provides a foundation for molecularly informed medicine in LUAD.
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7
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Dang F, Wei W. Targeting the acetylation signaling pathway in cancer therapy. Semin Cancer Biol 2022; 85:209-218. [PMID: 33705871 PMCID: PMC8423867 DOI: 10.1016/j.semcancer.2021.03.001] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2021] [Revised: 02/22/2021] [Accepted: 03/02/2021] [Indexed: 12/12/2022]
Abstract
Acetylation represents one of the major post-translational protein modifications, which introduces an acetyl functional group into amino acids such as the lysine residue to yield an acetate ester bond, neutralizing its positive charge. Regulation of protein functions by acetylation occurs in multiple ways, such as affecting protein stability, activity, localization, and interaction with other proteins or DNA. It has been well documented that the recruitment of histone acetyltransferases (HATs) and histone deacetylases (HDACs) to the transcriptional machinery can modulate histone acetylation status, which is directly involved in the dynamic regulation of genes controlling cell proliferation and division. Dysregulation of gene expression is involved in tumorigenesis and aberrant activation of histone deacetylases has been reported in several types of cancer. Moreover, there is growing body of evidence showing that acetylation is widely involved in non-histone proteins to impact their roles in various cellular processes including tumorigenesis. As such, small molecular compounds inhibiting HAT or HDAC enzymatic activities have been developed and investigated for therapeutic purpose. Here we review the recent progress in our understanding of protein acetylation and discuss the therapeutic potential of targeting the acetylation signaling pathway in cancer.
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Affiliation(s)
- Fabin Dang
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA
| | - Wenyi Wei
- Department of Pathology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA, 02215, USA.
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8
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Yao Y, Gu X, Xu X, Ge S, Jia R. Novel insights into RB1 mutation. Cancer Lett 2022; 547:215870. [PMID: 35964818 DOI: 10.1016/j.canlet.2022.215870] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2022] [Revised: 08/05/2022] [Accepted: 08/05/2022] [Indexed: 01/09/2023]
Abstract
Since the discovery of the retinoblastoma susceptibility gene (RB1) decades ago, RB1 has been regarded as a prototype tumor suppressor gene providing a paradigm for tumor genetic research. Constant research has updated the understanding of RB1-related pathways and their impact on tumor and nontumor diseases. Mutation of RB1 gene has been observed in multiple types of malignant tumors including prostate cancer, lung cancer, breast cancer, and almost every familial and sporadic case of retinoblastoma. Even if well-known and long-investigated, the application potential of RB1 mutation has not been fully tapped. In this review, we focus on the mechanism underlying RB1 mutation during oncogenesis. Therapeutically, we have further discussed potential clinical strategies by targeting RB1-mutated cancers. The unsolved problems and prospects of RB1 mutation are also discussed.
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Affiliation(s)
- Yiran Yao
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, China.
| | - Xiang Gu
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, China.
| | - Xiaofang Xu
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, China.
| | - Shengfang Ge
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, China.
| | - Renbing Jia
- Department of Ophthalmology, Ninth People's Hospital, Shanghai JiaoTong University School of Medicine, Shanghai, China; Shanghai Key Laboratory of Orbital Diseases and Ocular Oncology, Shanghai, China.
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9
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Zhou L, Ng DSC, Yam JC, Chen LJ, Tham CC, Pang CP, Chu WK. Post-translational modifications on the retinoblastoma protein. J Biomed Sci 2022; 29:33. [PMID: 35650644 PMCID: PMC9161509 DOI: 10.1186/s12929-022-00818-x] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 05/26/2022] [Indexed: 11/21/2022] Open
Abstract
The retinoblastoma protein (pRb) functions as a cell cycle regulator controlling G1 to S phase transition and plays critical roles in tumour suppression. It is frequently inactivated in various tumours. The functions of pRb are tightly regulated, where post-translational modifications (PTMs) play crucial roles, including phosphorylation, ubiquitination, SUMOylation, acetylation and methylation. Most PTMs on pRb are reversible and can be detected in non-cancerous cells, playing an important role in cell cycle regulation, cell survival and differentiation. Conversely, altered PTMs on pRb can give rise to anomalies in cell proliferation and tumourigenesis. In this review, we first summarize recent findings pertinent to how individual PTMs impinge on pRb functions. As many of these PTMs on pRb were published as individual articles, we also provide insights on the coordination, either collaborations and/or competitions, of the same or different types of PTMs on pRb. Having a better understanding of how pRb is post-translationally modulated should pave the way for developing novel and specific therapeutic strategies to treat various human diseases.
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Affiliation(s)
- Linbin Zhou
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Danny Siu-Chun Ng
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Jason C Yam
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China
| | - Li Jia Chen
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China
| | - Clement C Tham
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China
| | - Chi Pui Pang
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
- Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China
| | - Wai Kit Chu
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.
- Hong Kong Hub of Paediatric Excellence, The Chinese University of Hong Kong, Hong Kong, China.
- Department of Ophthalmology & Visual Sciences, The Chinese University of Hong Kong, Hong Kong Eye Hospital, 147K Argyle Street, Kowloon, Hong Kong, China.
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10
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Morales-de la Cruz X, Mandujano-Chávez A, Browne DR, Devarenne TP, Sánchez-Segura L, López MG, Lozoya-Gloria E. In Silico and Cellular Differences Related to the Cell Division Process between the A and B Races of the Colonial Microalga Botryococcus braunii. Biomolecules 2021; 11:biom11101463. [PMID: 34680096 PMCID: PMC8533097 DOI: 10.3390/biom11101463] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2021] [Revised: 09/23/2021] [Accepted: 09/25/2021] [Indexed: 11/23/2022] Open
Abstract
Botryococcus braunii produce liquid hydrocarbons able to be processed into combustion engine fuels. Depending on the growing conditions, the cell doubling time can be up to 6 days or more, which is a slow growth rate in comparison with other microalgae. Few studies have analyzed the cell cycle of B. braunii. We did a bioinformatic comparison between the protein sequences for retinoblastoma and cyclin-dependent kinases from the A (Yamanaka) and B (Showa) races, with those sequences from other algae and Arabidopsis thaliana. Differences in the number of cyclin-dependent kinases and potential retinoblastoma phosphorylation sites between the A and B races were found. Some cyclin-dependent kinases from both races seemed to be phylogenetically more similar to A. thaliana than to other microalgae. Microscopic observations were done using several staining procedures. Race A colonies, but not race B, showed some multinucleated cells without chlorophyll. An active mitochondrial net was detected in those multinucleated cells, as well as being defined in polyphosphate bodies. These observations suggest differences in the cell division processes between the A and B races of B. braunii.
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Affiliation(s)
- Xochitl Morales-de la Cruz
- Genetic Engineering Department, CINVESTAV-IPN Irapuato Unit, Irapuato 36824, Mexico; (X.M.-d.l.C.); (L.S.-S.)
| | | | - Daniel R. Browne
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA; (D.R.B.); (T.P.D.)
- Pacific Biosciences, Chicago, IL 60606, USA
| | - Timothy P. Devarenne
- Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, USA; (D.R.B.); (T.P.D.)
| | - Lino Sánchez-Segura
- Genetic Engineering Department, CINVESTAV-IPN Irapuato Unit, Irapuato 36824, Mexico; (X.M.-d.l.C.); (L.S.-S.)
| | - Mercedes G. López
- Biochemistry and Biotechnology Department, CINVESTAV-IPN Irapuato Unit, Irapuato 36824, Mexico;
| | - Edmundo Lozoya-Gloria
- Genetic Engineering Department, CINVESTAV-IPN Irapuato Unit, Irapuato 36824, Mexico; (X.M.-d.l.C.); (L.S.-S.)
- Correspondence: ; Tel.: +52-462-6239659
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11
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Kumar S, Tchounwou PB. Arsenic trioxide reduces the expression of E2F1, cyclin E, and phosphorylation of PI3K signaling molecules in acute leukemia cells. ENVIRONMENTAL TOXICOLOGY 2021; 36:1785-1792. [PMID: 34042274 PMCID: PMC8453914 DOI: 10.1002/tox.23299] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/06/2021] [Revised: 04/29/2021] [Accepted: 05/18/2021] [Indexed: 05/16/2023]
Abstract
Arsenic trioxide (ATO) has been used for the treatment of acute promyelocytic leukemia (APL). Although ATO modulates cell cycle progression and apoptosis in APL cells, its exact mechanism of action remains elusive. In this research, we investigated its effects on E2F1, cyclin E, p53, pRb, and PI3K signaling molecules by western blotting, immunocytochemistry and/or confocal imaging. We found that ATO inhibited the proliferation of APL cells through down-regulation of E2F1 and cyclin E expression, and stimulation of pRb. It also reduced the interaction of pRb and E2F1with binding to the E2F1 promoter, by stimulating pRb association. ATO also effected the phosphorylation of pRb at S608 and T373 residues and association of E2F1, pRb, and p53, simultaneously. However, in p53-knockdown NB4 cells, ATO did not significantly reduce E2F1 and cyclin E expression. Our findings demonstrate that ATO inhibits APL cell growth through reduced expression of E2F1, cyclin E, and stimulation of pRb. It also effected both interaction and association of E2F1, pRb, and p53 by phosphorylation of pRb at T373 and S608 residues and reduced phosphorylation of PI3K signaling molecules. This novel mode of action of ATO in APL cells may be useful for designing new APL drugs.
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Affiliation(s)
- Sanjay Kumar
- Cellomics and Toxicogenomics Research LaboratoryNIH/NIMHD‐RCMI Center for Environmental Health, College of Science, Engineering and Technology, Jackson State UniversityJacksonMississippi
- Department of life Sciences, School of Earth, Biological, and Environmental SciencesCentral UniversityGayaSouth BiharIndia
| | - Paul B. Tchounwou
- Cellomics and Toxicogenomics Research LaboratoryNIH/NIMHD‐RCMI Center for Environmental Health, College of Science, Engineering and Technology, Jackson State UniversityJacksonMississippi
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12
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Discovery of a potent, highly selective, and orally bioavailable inhibitor of CDK8 through a structure-based optimisation. Eur J Med Chem 2021; 218:113391. [PMID: 33823391 DOI: 10.1016/j.ejmech.2021.113391] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2021] [Revised: 03/16/2021] [Accepted: 03/17/2021] [Indexed: 12/24/2022]
Abstract
CDK8 is deregulated in multiple types of human cancer and is viewed as a therapeutic target for the treatment of the disease. Accordingly, the search for small-molecule inhibitors of CDK8 is being intensified. Capitalising on our initial discovery of AU1-100, a potent CDK8 inhibitor yet with a limited degree of kinase selectivity, a structure-based optimisation was carried out, with a series of new multi-substituted pyridines rationally designed, chemically prepared and biologically evaluated. Such endeavour has culminated in the identification of 42, a more potent CDK8 inhibitor with superior kinomic selectivity and oral bioavailability. The mechanism underlying the anti-proliferative effect of 42 on MV4-11 cells was studied, revealing that the compound arrested the G1 cell cycle and triggered apoptosis. The low risk of hepato- and cardio-toxicity of 42 was estimated. These findings merit further investigation of 42 as a targeted cancer therapeutic.
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Kim SJ, MacDonald JI, Dick FA. Phosphorylation of the RB C-terminus regulates condensin II release from chromatin. J Biol Chem 2021; 296:100108. [PMID: 33219128 PMCID: PMC7948394 DOI: 10.1074/jbc.ra120.016511] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 11/20/2020] [Indexed: 12/31/2022] Open
Abstract
The retinoblastoma tumor suppressor protein (RB) plays an important role in biological processes such as cell cycle control, DNA damage repair, epigenetic regulation, and genome stability. The canonical model of RB regulation is that cyclin-CDKs phosphorylate and render RB inactive in late G1/S, promoting entry into S phase. Recently, monophosphorylated RB species were described to have distinct cell-cycle-independent functions, suggesting that a phosphorylation code dictates diversity of RB function. However, a biologically relevant, functional role of RB phosphorylation at non-CDK sites has remained elusive. Here, we investigated S838/T841 dual phosphorylation, its upstream stimulus, and downstream functional output. We found that mimicking T-cell receptor activation in Jurkat leukemia cells induced sequential activation of downstream kinases including p38 MAPK and RB S838/T841 phosphorylation. This signaling pathway disrupts RB and condensin II interaction with chromatin. Using cells expressing a WT or S838A/T841A mutant RB fragment, we present evidence that deficiency for this phosphorylation event prevents condensin II release from chromatin.
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Affiliation(s)
- Seung J Kim
- London Regional Cancer Program, Lawson Health Research Institute, London, Ontario, Canada; Children's Health Research Institute, Lawson Health Research Institute, London, Ontario, Canada; Department of Biochemistry, Western University, London, Ontario, Canada
| | - James I MacDonald
- London Regional Cancer Program, Lawson Health Research Institute, London, Ontario, Canada; Children's Health Research Institute, Lawson Health Research Institute, London, Ontario, Canada; Department of Pathology and Laboratory Medicine, Western University, London, Ontario, Canada
| | - Frederick A Dick
- London Regional Cancer Program, Lawson Health Research Institute, London, Ontario, Canada; Children's Health Research Institute, Lawson Health Research Institute, London, Ontario, Canada; Department of Pathology and Laboratory Medicine, Western University, London, Ontario, Canada.
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14
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Pedreira-García WM, Pérez-Morales J, Chardón-Colón C, Cabán-Rivera J, Santiago-Cardona PG. Immunoblot Validation of Phospho-Specific Antibodies Using Lung Cancer Cell Lines. Methods Mol Biol 2021; 2279:75-90. [PMID: 33683687 PMCID: PMC8034249 DOI: 10.1007/978-1-0716-1278-1_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2024]
Abstract
The cancer phenotype is usually characterized by deregulated activity of a variety of cellular kinases, with consequent abnormal hyper-phosphorylation of their target proteins. Therefore, antibodies that allow the detection of phosphorylated versions of proteins have become important tools both preclinically in molecular cancer research, and at the clinical level by serving as tools in pathological analyses of tumors. In order to ensure reliable results, validation of the phospho-specificity of these antibodies is extremely important, since this ensures that they are indeed able to discriminate between the phosphorylated and unphosphorylated versions of the protein of interest, specifically recognizing the phosphorylated variant. A recommended validation approach consists in dephosphorylating the target protein and assessing if such dephosphorylation abrogates antigen immunoreactivity when using the phospho-specific antibody. In this chapter, we describe a protocol to validate the specificity of a phospho-specific antibody that recognizes a phosphorylated variant of the Retinoblastoma (Rb) protein in lung cancer cell lines. The protocol consists in the dephosphorylation of the Rb-containing protein lysates by treating them with bovine intestinal phosphatase, followed by assessment of the dephosphorylation by immunoblot.
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Affiliation(s)
- Wilfredo M Pedreira-García
- Biochemistry and Cancer Biology Divisions, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - Jaileene Pérez-Morales
- Biochemistry and Cancer Biology Divisions, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - Camille Chardón-Colón
- Biochemistry and Cancer Biology Divisions, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - Jennifer Cabán-Rivera
- Epidemiology Program, School of Public Health, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - Pedro G Santiago-Cardona
- Biochemistry and Cancer Biology Divisions, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico.
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15
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Kim S, Seo Y, Chowdhury T, Yu HJ, Lee CE, Kim KM, Kang H, Kim HJ, Park SJ, Kim K, Park CK. Inhibition of MUC1 exerts cell-cycle arrest and telomerase suppression in glioblastoma cells. Sci Rep 2020; 10:18238. [PMID: 33106534 PMCID: PMC7589558 DOI: 10.1038/s41598-020-75457-z] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Accepted: 10/12/2020] [Indexed: 01/13/2023] Open
Abstract
Mucin 1 (MUC1) is a transmembrane glycoprotein involved in tumorigenesis of diverse cancers. However, the role of MUC1 in glioblastoma (GBM) has not yet been fully explored. In this study, the anticancer mechanism of MUC1 suppression in GBM was investigated. The expression level of MUC1 was analyzed in human glioma and paired normal brain tissues. MUC1 was overexpressed in GBM and was negatively associated with overall survival. Moreover, we silenced MUC1 to investigate its effect in GBM cell lines and found that knockdown of MUC1 inhibited cell proliferation and resulted in cell cycle arrest at G1 phase. MUC1 silencing decreased the phosphorylation of RB1 and increased the expression of CDKN1B. Gene set enrichment analysis showed that a series of genes related to cell cycle, telomere maintenance and transforming growth factor Beta (TGF-β) signaling in epithelial mesenchymal transition (EMT) were influenced by MUC1 knockdown. Notably, the reduced TERT expression levels combined with impaired telomerase activity and the switching of telomere maintenance mechanism to alternative lengthening of telomeres (ALT) were observed after MUC1 knockdown. Our results support the role of MUC1 in oncological process in GBM which can be developed as a therapeutic target for cell cycle control and telomere maintenance mechanism.
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Affiliation(s)
- Sojin Kim
- Department of Neurosurgery, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
| | - Youngbeom Seo
- Department of Neurosurgery, Yeungnam University College of Medicine, Yeungnam University Hospital, Daegu, Republic of Korea
| | - Tamrin Chowdhury
- Department of Neurosurgery, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
| | - Hyeon Jong Yu
- Department of Neurosurgery, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
| | - Chae Eun Lee
- Department of Neurosurgery, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
| | - Kyung-Min Kim
- Department of Neurosurgery, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
| | - Ho Kang
- Department of Neurosurgery, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Korea
| | - Hak Jae Kim
- Department of Radiation Oncology, Seoul National University College of Medicine, Seoul Nation University Hospital, Seoul, Republic of Korea
| | - Soo-Ji Park
- Department of Biomedical Sciences and Department of Physiology, Korea University College of Medicine, Seoul, Republic of Korea
| | - Kyoungmi Kim
- Department of Biomedical Sciences and Department of Physiology, Korea University College of Medicine, Seoul, Republic of Korea
| | - Chul-Kee Park
- Department of Neurosurgery, Seoul National University College of Medicine, Seoul National University Hospital, 101 Daehak-ro, Jongno-gu, Seoul, 03080, Korea.
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16
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Retinoblastoma Tumor Suppressor Protein Roles in Epigenetic Regulation. Cancers (Basel) 2020; 12:cancers12102807. [PMID: 33003565 PMCID: PMC7600434 DOI: 10.3390/cancers12102807] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 09/19/2020] [Accepted: 09/27/2020] [Indexed: 12/14/2022] Open
Abstract
Simple Summary Loss of function of the retinoblastoma gene (RB1) is the rate-limiting step in the initiation of both the hereditary and sporadic forms of retinoblastoma tumor. Furthermore, loss of function of the retinoblastoma tumor suppressor protein (pRB) is frequently found in most human cancers. In retinoblastoma, tumor progression is driven by epigenetic changes following pRB loss. This review focuses on the diverse functions of pRB in epigenetic regulation. Abstract Mutations that result in the loss of function of pRB were first identified in retinoblastoma and since then have been associated with the propagation of various forms of cancer. pRB is best known for its key role as a transcriptional regulator during cell cycle exit. Beyond the ability of pRB to regulate transcription of cell cycle progression genes, pRB can remodel chromatin to exert several of its other biological roles. In this review, we discuss the diverse functions of pRB in epigenetic regulation including nucleosome mobilization, histone modifications, DNA methylation and non-coding RNAs.
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17
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NIR promotes progression of colorectal cancer through regulating RB. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2020; 1868:118856. [PMID: 32931817 DOI: 10.1016/j.bbamcr.2020.118856] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 12/31/2019] [Revised: 08/21/2020] [Accepted: 09/09/2020] [Indexed: 01/05/2023]
Abstract
NIR, a novel INHAT, negatively regulates the transcription activity of tumor repressor p53. However, if NIR functions in the tumorigenesis dependent on the regulation of p53 remains unknown. Here, we report that NIR promotes progression of colorectal cancer (CRC) through regulating RB function. Firstly, we found that NIR expression is upregulated in the human CRC tissues and significantly associated with the poor outcome of the patients. Sequence alignment shows that NIR contains an RB-binding motif LxCxE in its INHAT-2 domain. We demonstrate that NIR interacts with RB via INHAT-2 in CRC cells and promotes RB degradation through proteasome-mediated pathway. Further, either full-length GFP-NIR or GFP-NIR-INHAT2 facilitates poly-ubiquitination of RB. In addition, NIR inhibits RB acetylation by INHAT-2, suggesting NIR might promote RB degradation through inhibiting RB acetylation. Importantly, endogenous NIR is downregulated upon DNA damage, which is consistent with the upregulation of total level and acetylation of RB. We further show that Flag-NIR inhibits DNA damage-induced RB acetylation. Thus, downregulation of NIR might contribute to maintain the cellular homeostasis under DNA damage. Consequently, depletion of NIR inhibits cell proliferation and tumor growth in mouse xenografts. Taken together, we demonstrate that NIR promotes CRC progression partially through inhibiting RB acetylation and promoting RB degradation. Targeting NIR may provide a potential therapeutic strategy for NIR-upregulated CRC patients.
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18
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He W, Demas DM, Conde IP, Shajahan-Haq AN, Baumann WT. Mathematical modelling of breast cancer cells in response to endocrine therapy and Cdk4/6 inhibition. J R Soc Interface 2020; 17:20200339. [PMID: 32842890 PMCID: PMC7482571 DOI: 10.1098/rsif.2020.0339] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2020] [Accepted: 08/05/2020] [Indexed: 12/21/2022] Open
Abstract
Oestrogen receptor (ER)-positive breast cancer is responsive to a number of targeted therapies used clinically. Unfortunately, the continuous application of any targeted therapy often results in resistance to the therapy. Our ultimate goal is to use mathematical modelling to optimize alternating therapies that not only decrease proliferation but also stave off resistance. Toward this end, we measured levels of key proteins and proliferation over a 7-day time course in ER+ MCF-7 breast cancer cells. Treatments included endocrine therapy, either oestrogen deprivation, which mimics the effects of an aromatase inhibitor, or fulvestrant, an ER degrader. These data were used to calibrate a mathematical model based on key interactions between ER signalling and the cell cycle. We show that the calibrated model is capable of predicting the combination treatment of fulvestrant and oestrogen deprivation. Further, we show that we can add a new drug, palbociclib, to the model by measuring only two key proteins, cMyc and hyperphosphorylated RB1, and adjusting only parameters associated with the drug. The model is then able to predict the combination treatment of oestrogen deprivation and palbociclib. We illustrate the model's potential to explore protocols that limit proliferation and hold off resistance by not depending on any one therapy.
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Affiliation(s)
- Wei He
- Program in Genetics, Bioinformatics, and Computational Biology, VT BIOTRANS, Virginia Tech, Blacksburg, VA, USA
| | - Diane M. Demas
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, USA
| | - Isabel P. Conde
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, USA
| | - Ayesha N. Shajahan-Haq
- Department of Oncology, Lombardi Comprehensive Cancer Center, Georgetown University Medical Center, Washington, DC, USA
| | - William T. Baumann
- Department of Electrical and Computer Engineering, Virginia Tech, Blacksburg, VA, USA
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19
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Zluhan-Martínez E, Pérez-Koldenkova V, Ponce-Castañeda MV, Sánchez MDLP, García-Ponce B, Miguel-Hernández S, Álvarez-Buylla ER, Garay-Arroyo A. Beyond What Your Retina Can See: Similarities of Retinoblastoma Function between Plants and Animals, from Developmental Processes to Epigenetic Regulation. Int J Mol Sci 2020; 21:E4925. [PMID: 32664691 PMCID: PMC7404004 DOI: 10.3390/ijms21144925] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2020] [Revised: 06/29/2020] [Accepted: 07/07/2020] [Indexed: 12/15/2022] Open
Abstract
The Retinoblastoma protein (pRb) is a key cell cycle regulator conserved in a wide variety of organisms. Experimental analysis of pRb's functions in animals and plants has revealed that this protein participates in cell proliferation and differentiation processes. In addition, pRb in animals and its orthologs in plants (RBR), are part of highly conserved protein complexes which suggest the possibility that analogies exist not only between functions carried out by pRb orthologs themselves, but also in the structure and roles of the protein networks where these proteins are involved. Here, we present examples of pRb/RBR participation in cell cycle control, cell differentiation, and in the regulation of epigenetic changes and chromatin remodeling machinery, highlighting the similarities that exist between the composition of such networks in plants and animals.
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Affiliation(s)
- Estephania Zluhan-Martínez
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de Mexico, 3er Circuito Ext. Junto a J. Botánico, Ciudad Universitaria, UNAM 04510, Mexico; (E.Z.-M.); (M.d.l.P.S.); (B.G.-P.)
- Posgrado en Ciencias Biomédicas, Universidad Nacional Autónoma de México, Av. Universidad 3000, Coyoacán 04510, Mexico
| | - Vadim Pérez-Koldenkova
- Laboratorio Nacional de Microscopía Avanzada, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Av. Cuauhtémoc, 330. Col. Doctores, Alc. Cuauhtémoc 06720, Mexico;
| | - Martha Verónica Ponce-Castañeda
- Unidad de Investigación Médica en Enfermedades Infecciosas, Centro Médico Nacional SXXI, Instituto Mexicano del Seguro Social, Mexico City 06720, Mexico;
| | - María de la Paz Sánchez
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de Mexico, 3er Circuito Ext. Junto a J. Botánico, Ciudad Universitaria, UNAM 04510, Mexico; (E.Z.-M.); (M.d.l.P.S.); (B.G.-P.)
| | - Berenice García-Ponce
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de Mexico, 3er Circuito Ext. Junto a J. Botánico, Ciudad Universitaria, UNAM 04510, Mexico; (E.Z.-M.); (M.d.l.P.S.); (B.G.-P.)
| | - Sergio Miguel-Hernández
- Laboratorio de Citopatología Ambiental, Departamento de Morfología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Campus Zacatenco, Calle Wilfrido Massieu Esquina Cda, Manuel Stampa 07738, Mexico;
| | - Elena R. Álvarez-Buylla
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de Mexico, 3er Circuito Ext. Junto a J. Botánico, Ciudad Universitaria, UNAM 04510, Mexico; (E.Z.-M.); (M.d.l.P.S.); (B.G.-P.)
| | - Adriana Garay-Arroyo
- Laboratorio de Genética Molecular, Epigenética, Desarrollo y Evolución de Plantas, Instituto de Ecología, Universidad Nacional Autónoma de Mexico, 3er Circuito Ext. Junto a J. Botánico, Ciudad Universitaria, UNAM 04510, Mexico; (E.Z.-M.); (M.d.l.P.S.); (B.G.-P.)
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20
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Butler MB, Short NE, Maniou E, Alexandre P, Greene NDE, Copp AJ, Galea GL. Rho kinase-dependent apical constriction counteracts M-phase apical expansion to enable mouse neural tube closure. J Cell Sci 2019; 132:jcs.230300. [PMID: 31182644 PMCID: PMC6633395 DOI: 10.1242/jcs.230300] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2019] [Accepted: 05/30/2019] [Indexed: 12/18/2022] Open
Abstract
Cellular generation of mechanical forces required to close the presumptive spinal neural tube, the 'posterior neuropore' (PNP), involves interkinetic nuclear migration (INM) and apical constriction. Both processes change the apical surface area of neuroepithelial cells, but how they are biomechanically integrated is unknown. Rho kinase (Rock; herein referring to both ROCK1 and ROCK2) inhibition in mouse whole embryo culture progressively widens the PNP. PNP widening is not caused by increased mechanical tension opposing closure, as evidenced by diminished recoil following laser ablation. Rather, Rock inhibition diminishes neuroepithelial apical constriction, producing increased apical areas in neuroepithelial cells despite diminished tension. Neuroepithelial apices are also dynamically related to INM progression, with the smallest dimensions achieved in cells positive for the pan-M phase marker Rb phosphorylated at S780 (pRB-S780). A brief (2 h) Rock inhibition selectively increases the apical area of pRB-S780-positive cells, but not pre-anaphase cells positive for phosphorylated histone 3 (pHH3+). Longer inhibition (8 h, more than one cell cycle) increases apical areas in pHH3+ cells, suggesting cell cycle-dependent accumulation of cells with larger apical surfaces during PNP widening. Consequently, arresting cell cycle progression with hydroxyurea prevents PNP widening following Rock inhibition. Thus, Rock-dependent apical constriction compensates for the PNP-widening effects of INM to enable progression of closure.This article has an associated First Person interview with the first authors of the paper.
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Affiliation(s)
- Max B Butler
- Developmental Biology and Cancer, UCL GOS Institute of Child Health, London WC1N 1EH, UK
| | - Nina E Short
- Developmental Biology and Cancer, UCL GOS Institute of Child Health, London WC1N 1EH, UK
| | - Eirini Maniou
- Developmental Biology and Cancer, UCL GOS Institute of Child Health, London WC1N 1EH, UK
| | - Paula Alexandre
- Developmental Biology and Cancer, UCL GOS Institute of Child Health, London WC1N 1EH, UK
| | - Nicholas D E Greene
- Developmental Biology and Cancer, UCL GOS Institute of Child Health, London WC1N 1EH, UK
| | - Andrew J Copp
- Developmental Biology and Cancer, UCL GOS Institute of Child Health, London WC1N 1EH, UK
| | - Gabriel L Galea
- Developmental Biology and Cancer, UCL GOS Institute of Child Health, London WC1N 1EH, UK .,Comparative Bioveterinary Sciences, Royal Veterinary College, London NW1 0TU, UK
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21
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Lee Y, Lahens NF, Zhang S, Bedont J, Field JM, Sehgal A. G1/S cell cycle regulators mediate effects of circadian dysregulation on tumor growth and provide targets for timed anticancer treatment. PLoS Biol 2019; 17:e3000228. [PMID: 31039152 PMCID: PMC6490878 DOI: 10.1371/journal.pbio.3000228] [Citation(s) in RCA: 63] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2018] [Accepted: 03/27/2019] [Indexed: 12/31/2022] Open
Abstract
Circadian disruption has multiple pathological consequences, but the underlying mechanisms are largely unknown. To address such mechanisms, we subjected transformed cultured cells to chronic circadian desynchrony (CCD), mimicking a chronic jet-lag scheme, and assayed a range of cellular functions. The results indicated a specific circadian clock–dependent increase in cell proliferation. Transcriptome analysis revealed up-regulation of G1/S phase transition genes (myelocytomatosis oncogene cellular homolog [Myc], cyclin D1/3, chromatin licensing and DNA replication factor 1 [Cdt1]), concomitant with increased phosphorylation of the retinoblastoma (RB) protein by cyclin-dependent kinase (CDK) 4/6 and increased G1-S progression. Phospho-RB (Ser807/811) was found to oscillate in a circadian fashion and exhibit phase-shifted rhythms in circadian desynchronized cells. Consistent with circadian regulation, a CDK4/6 inhibitor approved for cancer treatment reduced growth of cultured cells and mouse tumors in a time-of-day–specific manner. Our study identifies a mechanism that underlies effects of circadian disruption on tumor growth and underscores the use of treatment timed to endogenous circadian rhythms. A study of “jet-lagged” cells reveals a specific molecular mechanism regulating cell proliferation that it impacted by circadian disruption, underscoring the importance of administering anti-cancer treatment at a specific time of day. Circadian misalignment caused by altered sleep–wake cycles, shift work, or frequent jet lag increases susceptibility to several disorders, including cancer. However, the mechanisms by which circadian disruption contributes to disease are not well understood, and so we addressed this issue by investigating the molecular, cellular, and biochemical consequences of chronic circadian desynchronization. Our studies using cancer cell or tumor tissue models show that chronic circadian desynchronization induces multiple oncogenic pathways to promote cell proliferation. In particular, chronic circadian desynchronization promotes phosphorylation of the retinoblastoma (RB) protein, thereby favoring G1/S phase cell cycle progression. Consistent with these findings, the antiproliferative activity of a selective inhibitor of the enzyme that phosphorylates RB has time-of-day–specific effects on cancer cells and mouse tumors, but this time dependence is abrogated by chronic jet-lag conditions. These data suggest a circadian regulation of G1/S cell cycle progression and provide an important molecular rationale for time-of-day–specific treatment of cancer patients, also known as chronotherapy.
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Affiliation(s)
- Yool Lee
- Penn Chronobiology, Howard Hughes Medical Institute, Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Nicholas F. Lahens
- Institute for Translational Medicine and Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Shirley Zhang
- Penn Chronobiology, Howard Hughes Medical Institute, Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Joseph Bedont
- Penn Chronobiology, Howard Hughes Medical Institute, Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Jeffrey M. Field
- Department of Systems Pharmacology and Translational Therapeutics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Amita Sehgal
- Penn Chronobiology, Howard Hughes Medical Institute, Department of Neuroscience, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
- * E-mail:
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22
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Bisphenol S promotes the cell cycle progression and cell proliferation through ERα-cyclin D-CDK4/6-pRb pathway in MCF-7 breast cancer cells. Toxicol Appl Pharmacol 2019; 366:75-82. [DOI: 10.1016/j.taap.2019.01.017] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2018] [Revised: 01/15/2019] [Accepted: 01/19/2019] [Indexed: 11/20/2022]
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23
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Thomas NA, Abraham RG, Dedi B, Krucher NA. Targeting retinoblastoma protein phosphorylation in combination with EGFR inhibition in pancreatic cancer cells. Int J Oncol 2018; 54:527-536. [PMID: 30535494 PMCID: PMC6317693 DOI: 10.3892/ijo.2018.4658] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 11/16/2018] [Indexed: 12/24/2022] Open
Abstract
Pancreatic ductal adenocarcinoma (PDAC) remains a particularly lethal disease that is resistant to targeted therapies. Tyrosine kinase inhibitors (TKIs), including erlotinib and gefitinib, which block the action of the human epidermal growth factor receptor type 1 receptor, provide small increases in patient survival when administered with gemcitabine. The retinoblastoma (Rb) tumor suppressor protein is an additional target in pancreatic cancer, due to its documented inactivation in PDAC. The present study, using cell number, apoptosis and immunoblotting assays, aimed to evaluate the effects of activation of the Rb tumor suppressor via dephosphorylation by small interfering RNA-mediated phosphatase activation. In the Panc1, MIAPaCa-2 and Capan-2 pancreatic cancer cell lines, and in normal H6c7 cells, the effects of phosphatase activation on Rb were revealed to be dependent on expression of the p16 tumor suppressor, which regulates Rb phosphorylation. Phosphatase activation had no effect on non-transformed pancreatic epithelial cells. When comparing kinase inhibition with phosphatase activation, it was demonstrated that kinase inhibition reduced proliferation, whereas phosphatase activation induced apoptosis. Both treatments together resulted in a greater reduction of pancreatic cancer cells than either treatment alone. In addition, the effects of combination treatment of phosphatase activation with TKIs on cell number and activation of the signal transducer and activator of transcription 3 (STAT3) resistance pathway were determined. The combination of Rb phosphatase activation with TKIs resulted in a greater reduction in cell number compared with either treatment alone, without STAT3 pathway activation. These data suggested that targeting Rb phosphorylation by activating phosphatase may be a rational strategy to inhibit pancreatic tumor cell growth, without activation of acquired resistance.
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Affiliation(s)
- Nimmi A Thomas
- Department of Biology, Pace University, Pleasantville, NY 10570, USA
| | - Rita G Abraham
- Department of Biology, Pace University, Pleasantville, NY 10570, USA
| | - Brixhilda Dedi
- Department of Biology, Pace University, Pleasantville, NY 10570, USA
| | - Nancy A Krucher
- Department of Biology, Pace University, Pleasantville, NY 10570, USA
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24
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Pérez-Morales J, Mejías-Morales D, Rivera-Rivera S, González-Flores J, González-Loperena M, Cordero-Báez FY, Pedreira-García WM, Chardón-Colón C, Cabán-Rivera J, Cress WD, Gordian ER, Muñoz-Antonia T, Cabrera-Ríos M, Isidro A, Coppola D, Rosa M, Boyle TA, Izumi V, Koomen JM, Santiago-Cardona PG. Hyper-phosphorylation of Rb S249 together with CDK5R2/p39 overexpression are associated with impaired cell adhesion and epithelial-to-mesenchymal transition: Implications as a potential lung cancer grading and staging biomarker. PLoS One 2018; 13:e0207483. [PMID: 30452490 PMCID: PMC6242691 DOI: 10.1371/journal.pone.0207483] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 10/31/2018] [Indexed: 01/15/2023] Open
Abstract
Prediction of lung cancer metastasis relies on post-resection assessment of tumor histology, which is a severe limitation since only a minority of lung cancer patients are diagnosed with resectable disease. Therefore, characterization of metastasis-predicting biomarkers in pre-resection small biopsy specimens is urgently needed. Here we report a biomarker consisting of the phosphorylation of the retinoblastoma protein (Rb) on serine 249 combined with elevated p39 expression. This biomarker correlates with epithelial-to-mesenchymal transition traits in non-small cell lung carcinoma (NSCLC) cells. Immunohistochemistry staining of NSCLC tumor microarrays showed that strong phospho-Rb S249 staining positively correlated with tumor grade specifically in the squamous cell carcinoma (SCC) subtype. Strong immunoreactivity for p39 positively correlated with tumor stage, lymph node invasion, and distant metastases, also in SCC. Linear regression analyses showed that the combined scoring for phospho-Rb S249, p39 and E-cadherin in SCC is even more accurate at predicting tumor staging, relative to each score individually. We propose that combined immunohistochemistry staining of NSCLC samples for Rb phosphorylation on S249, p39, and E-cadherin protein expression could aid in the assessment of tumor staging and metastatic potential when tested in small primary tumor biopsies. The intense staining for phospho-Rb S249 that we observed in high grade SCC could also aid in the precise sub-classification of poorly differentiated SCCs.
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Affiliation(s)
- Jaileene Pérez-Morales
- Biochemistry and Cancer Biology Divisions, Basic Science Department, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - Darielys Mejías-Morales
- Biochemistry and Cancer Biology Divisions, Basic Science Department, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - Stephanie Rivera-Rivera
- Biochemistry and Cancer Biology Divisions, Basic Science Department, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - Jonathan González-Flores
- Biochemistry and Cancer Biology Divisions, Basic Science Department, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - Mónica González-Loperena
- Biochemistry and Cancer Biology Divisions, Basic Science Department, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - Fernando Y. Cordero-Báez
- Biochemistry and Cancer Biology Divisions, Basic Science Department, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - Wilfredo M. Pedreira-García
- Biochemistry and Cancer Biology Divisions, Basic Science Department, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - Camille Chardón-Colón
- Biochemistry and Cancer Biology Divisions, Basic Science Department, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - Jennifer Cabán-Rivera
- Biochemistry and Cancer Biology Divisions, Basic Science Department, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - W. Douglas Cress
- Molecular Oncology and Thoracic Oncology Departments, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
| | - Edna R. Gordian
- Molecular Oncology and Thoracic Oncology Departments, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
| | - Teresita Muñoz-Antonia
- Molecular Oncology and Thoracic Oncology Departments, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
| | - Mauricio Cabrera-Ríos
- Department of Industrial Engineering, University of Puerto Rico at Mayagüez, Mayagüez, Puerto Rico
| | - Angel Isidro
- Physiology Division, Basic Science Department, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
| | - Domenico Coppola
- Anatomic Pathology, Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
| | - Marilin Rosa
- Anatomic Pathology, Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
| | - Theresa A. Boyle
- Anatomic Pathology, Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
| | - Victoria Izumi
- Proteomics, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
| | - John M. Koomen
- Molecular Oncology and Thoracic Oncology Departments, H. Lee Moffitt Cancer Center and Research Institute, Tampa, Florida, United States of America
| | - Pedro G. Santiago-Cardona
- Biochemistry and Cancer Biology Divisions, Basic Science Department, Ponce Health Sciences University-Ponce Research Institute, Ponce, Puerto Rico
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The RASSF6 Tumor Suppressor Protein Regulates Apoptosis and Cell Cycle Progression via Retinoblastoma Protein. Mol Cell Biol 2018; 38:MCB.00046-18. [PMID: 29891515 DOI: 10.1128/mcb.00046-18] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2018] [Accepted: 06/07/2018] [Indexed: 02/06/2023] Open
Abstract
RASSF6 is a member of the tumor suppressor Ras association domain family (RASSF) proteins. RASSF6 is frequently suppressed in human cancers, and its low expression level is associated with poor prognosis. RASSF6 regulates cell cycle arrest and apoptosis and plays a tumor suppressor role. Mechanistically, RASSF6 blocks MDM2-mediated p53 degradation and enhances p53 expression. However, RASSF6 also induces cell cycle arrest and apoptosis in a p53-negative background, which implies that the tumor suppressor function of RASSF6 does not depend solely on p53. In this study, we revealed that RASSF6 mediates cell cycle arrest and apoptosis via pRb. RASSF6 enhances the interaction between pRb and protein phosphatase. RASSF6 also enhances P16INK4A and P14ARF expression by suppressing BMI1. In this way, RASSF6 increases unphosphorylated pRb and augments the interaction between pRb and E2F1. Moreover, RASSF6 induces TP73 target genes via pRb and E2F1 in a p53-negative background. Finally, we confirmed that RASSF6 depletion induces polyploid cells in p53-negative HCT116 cells. In conclusion, RASSF6 behaves as a tumor suppressor in cancers with loss of function of p53, and pRb is implicated in this function of RASSF6.
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Abstract
The retinoblastoma tumor suppressor protein (pRb) is a preeminent tumor suppressor that acts as a cell cycle repressor, specifically as an inhibitor of the G1-S transition of the cell cycle . pRb is a phosphoprotein whose function is repressed by extensive phosphorylation in several key residues, and therefore, pRb's phosphorylation status has become a surrogate for pRb activity. In particular, hyperphosphorylation of pRb has been associated with pathological states such as cancer, and therefore, assessing pRb's phosphorylation status is increasingly gaining diagnostic and prognostic value, may be used to inform therapeutic decisions, and is also an important tool for the cancer biologists seeking an understanding of the molecular etiology of cancer. In this chapter, we discuss an immunoblot protocol to detect pRb phosphorylation in two residues, serine 612 and threonine 821, in protein extracts from cancer cells.
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27
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Meng F, Li X, Ren H, Qian J. In Vivo Detection and Analysis of Rb Protein SUMOylation in Human Cells. J Vis Exp 2017. [PMID: 29155755 DOI: 10.3791/56096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The post-translational modifications of proteins are critical for the proper regulation of intracellular signal transduction. Among these modifications, small ubiquitin-related modifier (SUMO) is a ubiquitin-like protein that is covalently attached to the lysine residues of a variety of target proteins to regulate cellular processes, such as gene transcription, DNA repair, protein interaction and degradation, subcellular transport, and signal transduction. The most common approach to detecting protein SUMOylation is based on the expression and purification of recombinant tagged proteins in bacteria, allowing for an in vitro biochemical reaction which is simple and suitable for addressing mechanistic questions. However, due to the complexity of the process of SUMOylation in vivo, it is more challenging to detect and analyze protein SUMOylation in cells, especially when under endogenous conditions. A recent study by the authors of this paper revealed that endogenous retinoblastoma (Rb) protein, a tumor suppressor that is vital to the negative regulation of the cell cycle progression, is specifically SUMOylated at the early G1 phase. This paper describes a protocol for the detection and analysis of Rb SUMOylation under both endogenous and exogenous conditions in human cells. This protocol is appropriate for the phenotypical and functional investigation of the SUMO-modification of Rb, as well as many other SUMO-targeted proteins, in human cells.
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Affiliation(s)
- Fengxi Meng
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University
| | - Xiaofeng Li
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University
| | - Hui Ren
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University
| | - Jiang Qian
- Department of Ophthalmology, Eye and ENT Hospital of Fudan University; Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University;
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Sheldon LA. Inhibition of E2F1 activity and cell cycle progression by arsenic via retinoblastoma protein. Cell Cycle 2017; 16:2058-2072. [PMID: 28880708 DOI: 10.1080/15384101.2017.1338221] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The regulation of cell cycle progression by steroid hormones and growth factors is important for maintaining normal cellular processes including development and cell proliferation. Deregulated progression through the G1/S and G2/M cell cycle transitions can lead to uncontrolled cell proliferation and cancer. The transcription factor E2F1, a key cell cycle regulator, targets genes encoding proteins that regulate cell cycle progression through the G1/S transition as well as proteins important in DNA repair and apoptosis. E2F1 expression and activity is inhibited by inorganic arsenic (iAs) that has a dual role as a cancer therapeutic and as a toxin that leads to diseases including cancer. An understanding of what underlies this dichotomy will contribute to understanding how to use iAs as a more effective therapeutic and also how to treat cancers that iAs promotes. Here, we show that quiescent breast adenocarcinoma MCF-7 cells treated with 17-β estradiol (E2) progress through the cell cycle, but few cells treated with E2 + iAs progress from G1 into S-phase due to a block in cell cycle progression. Our data support a model in which iAs inhibits the dissociation of E2F1 from the tumor suppressor, retinoblastoma protein (pRB) due to changes in pRB phosphorylation which leads to decreased E2F1 transcriptional activity. These findings present an explanation for how iAs can disrupt cell cycle progression through E2F1-pRB and has implications for how iAs acts as a cancer therapeutic as well as how it may promote tumorigenesis through decreased DNA repair.
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Affiliation(s)
- Lynn A Sheldon
- a Geisel School of Medicine at Dartmouth, Department of Molecular and Systems Biology , Hanover , NH , USA
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29
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Munro S, La Thangue NB. Linking H1 with chromatin and growth control. Mol Cell Oncol 2017; 4:e1360977. [PMID: 29209648 PMCID: PMC5706956 DOI: 10.1080/23723556.2017.1360977] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2017] [Revised: 07/25/2017] [Accepted: 07/25/2017] [Indexed: 11/02/2022]
Abstract
The retinoblastoma protein (pRb) is considered to be one of the key regulators of cell proliferation. Here we describe our recent findings that linker histone H1.2 is an interaction partner for pRb and impacts upon the genome-wide chromatin binding properties of pRb. Consequently, H1.2 influences transcriptional repression and cell cycle control.
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Affiliation(s)
- Shonagh Munro
- Laboratory of Cancer Biology, Department of Oncology, Medical Sciences Division, University of Oxford, Old Road Campus Research Building, Old Road Campus, off Roosevelt Drive, Oxford, OX3 7DQ, United Kingdom
| | - Nicholas B. La Thangue
- Laboratory of Cancer Biology, Department of Oncology, Medical Sciences Division, University of Oxford, Old Road Campus Research Building, Old Road Campus, off Roosevelt Drive, Oxford, OX3 7DQ, United Kingdom
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30
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Mita MM, Mita AC, Moseley JL, Poon J, Small KA, Jou YM, Kirschmeier P, Zhang D, Zhu Y, Statkevich P, Sankhala KK, Sarantopoulos J, Cleary JM, Chirieac LR, Rodig SJ, Bannerji R, Shapiro GI. Phase 1 safety, pharmacokinetic and pharmacodynamic study of the cyclin-dependent kinase inhibitor dinaciclib administered every three weeks in patients with advanced malignancies. Br J Cancer 2017; 117:1258-1268. [PMID: 28859059 PMCID: PMC5672931 DOI: 10.1038/bjc.2017.288] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 06/15/2017] [Accepted: 07/28/2017] [Indexed: 12/28/2022] Open
Abstract
Background: Dinaciclib is a potent inhibitor of cell cycle and transcriptional cyclin-dependent kinases. This Phase 1 study evaluated the safety, tolerability and pharmacokinetics of various dosing schedules of dinaciclib in advanced solid tumour patients and assessed pharmacodynamic and preliminary anti-tumour activity. Methods: In part 1, patients were enrolled in escalating cohorts of 2-h infusions administered once every 3 weeks, utilising an accelerated titration design until a recommended phase 2 dose (RP2D) was defined. In part 2, 8- and 24-h infusions were evaluated. Pharmacokinetic parameters were determined for all schedules. Pharmacodynamic effects were assessed with an ex vivo stimulated lymphocyte proliferation assay performed in whole blood. Effects of dinaciclib on retinoblastoma (Rb) phosphorylation and other CDK targets were evaluated in skin and tumour biopsies. In addition to tumour size, metabolic response was evaluated by 18F-fluorodeoxyglucose-positron emission tomography. Results: Sixty-one patients were enrolled to parts 1 and 2. The RP2Ds were 50, 7.4 and 10.4 mg m−2 as 2- 8- and 24-hour infusions, respectively. Dose-limiting toxicities included pancytopenia, neutropenic fever, elevated transaminases, hyperuricemia and hypotension. Pharmacokinetics demonstrated rapid distribution and a short plasma half-life. Dinaciclib suppressed proliferation of stimulated lymphocytes. In skin and tumour biopsies, dinaciclib reduced Rb phosphorylation at CDK2 phospho-sites and modulated expression of cyclin D1 and p53, suggestive of CDK9 inhibition. Although there were no RECIST responses, eight patients had prolonged stable disease and received between 6 and 30 cycles. Early metabolic responses occurred. Conclusions: Dinaciclib is tolerable at doses demonstrating target engagement in surrogate and tumour tissue.
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Affiliation(s)
- Monica M Mita
- Institute for Drug Development, Cancer Therapy and Research Center at University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Alain C Mita
- Institute for Drug Development, Cancer Therapy and Research Center at University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - Jennifer L Moseley
- Institute for Drug Development, Cancer Therapy and Research Center at University of Texas Health Science Center, San Antonio, TX 78229, USA
| | | | | | | | | | - Da Zhang
- Merck & Co., Inc., Kenilworth, NJ 07033, USA
| | - Yali Zhu
- Merck & Co., Inc., Kenilworth, NJ 07033, USA
| | | | - Kamelesh K Sankhala
- Institute for Drug Development, Cancer Therapy and Research Center at University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - John Sarantopoulos
- Institute for Drug Development, Cancer Therapy and Research Center at University of Texas Health Science Center, San Antonio, TX 78229, USA
| | - James M Cleary
- Early Drug Development Center, Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA.,Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02215, USA
| | - Lucian R Chirieac
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02215, USA
| | - Scott J Rodig
- Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02215, USA
| | | | - Geoffrey I Shapiro
- Early Drug Development Center, Department of Medical Oncology, Dana-Farber Cancer Institute, 450 Brookline Avenue, Boston, MA 02215, USA.,Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, MA 02215, USA
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31
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Vélez-Cruz R, Johnson DG. The Retinoblastoma (RB) Tumor Suppressor: Pushing Back against Genome Instability on Multiple Fronts. Int J Mol Sci 2017; 18:ijms18081776. [PMID: 28812991 PMCID: PMC5578165 DOI: 10.3390/ijms18081776] [Citation(s) in RCA: 67] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Revised: 08/13/2017] [Accepted: 08/13/2017] [Indexed: 12/13/2022] Open
Abstract
The retinoblastoma (RB) tumor suppressor is known as a master regulator of the cell cycle. RB is mutated or functionally inactivated in the majority of human cancers. This transcriptional regulator exerts its function in cell cycle control through its interaction with the E2F family of transcription factors and with chromatin remodelers and modifiers that contribute to the repression of genes important for cell cycle progression. Over the years, studies have shown that RB participates in multiple processes in addition to cell cycle control. Indeed, RB is known to interact with over 200 different proteins and likely exists in multiple complexes. RB, in some cases, acts through its interaction with E2F1, other members of the pocket protein family (p107 and p130), and/or chromatin remodelers and modifiers. RB is a tumor suppressor with important chromatin regulatory functions that affect genomic stability. These functions include the role of RB in DNA repair, telomere maintenance, chromosome condensation and cohesion, and silencing of repetitive regions. In this review we will discuss recent advances in RB biology related to RB, partner proteins, and their non-transcriptional functions fighting back against genomic instability.
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Affiliation(s)
- Renier Vélez-Cruz
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, 1808 Park Road 1C, P.O. Box 389, Smithville, TX 78957, USA.
- Department of Biochemistry, Midwestern University, Chicago College of Osteopathic Medicine, 555 31st Street, Downers Grove, IL 60515, USA.
| | - David G Johnson
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, 1808 Park Road 1C, P.O. Box 389, Smithville, TX 78957, USA.
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Barnoud T, Schmidt ML, Donninger H, Clark GJ. The role of the NORE1A tumor suppressor in Oncogene-Induced Senescence. Cancer Lett 2017; 400:30-36. [PMID: 28455242 PMCID: PMC5502528 DOI: 10.1016/j.canlet.2017.04.030] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Revised: 04/18/2017] [Accepted: 04/19/2017] [Indexed: 12/14/2022]
Abstract
The Ras genes are the most frequently mutated oncogenes in human cancer. However, Ras biology is quite complex. While Ras promotes tumorigenesis by regulating numerous growth promoting pathways, activated Ras can paradoxically also lead to cell cycle arrest, death, and Oncogene-Induced Senescence (OIS). OIS is thought to be a critical pathway that serves to protect cells against aberrant Ras signaling. Multiple reports have highlighted the importance of the p53 and Rb tumor suppressors in Ras mediated OIS. However, until recently, the molecular mechanisms connecting Ras to these proteins remained unknown. The RASSF family of tumor suppressors has recently been identified as direct effectors of Ras. One of these members, NORE1A (RASSF5), may be the missing link between Ras-induced senescence and the regulation of p53 and Rb. This occurs both quantitatively, by promoting protein stability, as well as qualitatively via promoting critical pro-senescent post-translational modifications. Here we review the mechanisms by which NORE1A can activate OIS as a barrier against Ras-mediated transformation, and how this could lead to improved therapeutic strategies against cancers having lost NORE1A expression.
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Affiliation(s)
- Thibaut Barnoud
- Program in Molecular and Cellular Oncogenesis, The Wistar Institute, Philadelphia PA 19104, USA
| | - M Lee Schmidt
- Department of Pharmacology and Toxicology, University of Louisville, KY 40202, USA
| | | | - Geoffrey J Clark
- Department of Pharmacology and Toxicology, University of Louisville, KY 40202, USA.
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Beaumatin F, El Dhaybi M, Bobo C, Verdier M, Priault M. Bcl-x L deamidation and cancer: Charting the fame trajectories of legitimate child and hidden siblings. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2017. [PMID: 28645514 DOI: 10.1016/j.bbamcr.2017.06.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Bcl-2 family proteins control programmed cell death through a complex network of interactions within and outside of this family, that are modulated by post-translational modifications (PTM). Bcl-xL, an anti-apoptotic member of this family, is overexpressed in a number of cancers, plays an important role in tumorigenesis and is correlated with drug resistance. Bcl-xL is susceptible to a number of different PTMs. Here, we focus on deamidation. We will first provide an overview of protein deamidation. We will then review how the apoptotic and autophagic functions of Bcl-xL are modified by this PTM, and how this impacts on its oncogenic properties. Possible therapeutic outcomes will also be discussed. Finally, we will highlight how the specific case of Bcl-xL deamidation provides groundings to revisit some concepts related to protein deamidation in general.
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Affiliation(s)
- Florian Beaumatin
- CNRS, Institut de Biochimie et de Génétique Cellulaires, UMR5095, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France; Université de Bordeaux, Institut de Biochimie et de Génétique Cellulaires, UMR5095, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France
| | - Mohamad El Dhaybi
- CNRS, Institut de Biochimie et de Génétique Cellulaires, UMR5095, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France; Université de Bordeaux, Institut de Biochimie et de Génétique Cellulaires, UMR5095, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France; EA 3842, Homéostasie Cellulaire et Pathologies, Université de Limoges, 2, rue du Docteur Marcland, 87025 Limoges Cedex, France
| | - Claude Bobo
- CNRS, Institut de Biochimie et de Génétique Cellulaires, UMR5095, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France; Université de Bordeaux, Institut de Biochimie et de Génétique Cellulaires, UMR5095, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France
| | - Mireille Verdier
- EA 3842, Homéostasie Cellulaire et Pathologies, Université de Limoges, 2, rue du Docteur Marcland, 87025 Limoges Cedex, France
| | - Muriel Priault
- CNRS, Institut de Biochimie et de Génétique Cellulaires, UMR5095, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France; Université de Bordeaux, Institut de Biochimie et de Génétique Cellulaires, UMR5095, 1 Rue Camille Saint-Saëns, 33077 Bordeaux, France.
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Abstract
In this review, Dyson summarizes some recent developments in pRB research and focuses on progress toward answers for the three fundamental questions that sit at the heart of the pRB literature: What does pRB do? How does the inactivation of RB change the cell? How can our knowledge of RB function be exploited to provide better treatment for cancer patients? The retinoblastoma susceptibility gene (RB1) was the first tumor suppressor gene to be molecularly defined. RB1 mutations occur in almost all familial and sporadic forms of retinoblastoma, and this gene is mutated at variable frequencies in a variety of other human cancers. Because of its early discovery, the recessive nature of RB1 mutations, and its frequency of inactivation, RB1 is often described as a prototype for the class of tumor suppressor genes. Its gene product (pRB) regulates transcription and is a negative regulator of cell proliferation. Although these general features are well established, a precise description of pRB's mechanism of action has remained elusive. Indeed, in many regards, pRB remains an enigma. This review summarizes some recent developments in pRB research and focuses on progress toward answers for the three fundamental questions that sit at the heart of the pRB literature: What does pRB do? How does the inactivation of RB change the cell? How can our knowledge of RB function be exploited to provide better treatment for cancer patients?
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35
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Potapova TA, Seidel CW, Box AC, Rancati G, Li R. Transcriptome analysis of tetraploid cells identifies cyclin D2 as a facilitator of adaptation to genome doubling in the presence of p53. Mol Biol Cell 2016; 27:3065-3084. [PMID: 27559130 PMCID: PMC5063615 DOI: 10.1091/mbc.e16-05-0268] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/16/2016] [Indexed: 01/12/2023] Open
Abstract
Tetraploidization, or genome doubling, is a prominent event in tumorigenesis, primarily because cell division in polyploid cells is error-prone and produces aneuploid cells. This study investigates changes in gene expression evoked in acute and adapted tetraploid cells and their effect on cell-cycle progression. Acute polyploidy was generated by knockdown of the essential regulator of cytokinesis anillin, which resulted in cytokinesis failure and formation of binucleate cells, or by chemical inhibition of Aurora kinases, causing abnormal mitotic exit with formation of single cells with aberrant nuclear morphology. Transcriptome analysis of these acute tetraploid cells revealed common signatures of activation of the tumor-suppressor protein p53. Suppression of proliferation in these cells was dependent on p53 and its transcriptional target, CDK inhibitor p21. Rare proliferating tetraploid cells can emerge from acute polyploid populations. Gene expression analysis of single cell-derived, adapted tetraploid clones showed up-regulation of several p53 target genes and cyclin D2, the activator of CDK4/6/2. Overexpression of cyclin D2 in diploid cells strongly potentiated the ability to proliferate with increased DNA content despite the presence of functional p53. These results indicate that p53-mediated suppression of proliferation of polyploid cells can be averted by increased levels of oncogenes such as cyclin D2, elucidating a possible route for tetraploidy-mediated genomic instability in carcinogenesis.
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Affiliation(s)
| | | | - Andrew C Box
- Stowers Institute for Medical Research, Kansas City, MO 64110
| | - Giulia Rancati
- Institute of Medical Biology, Agency for Science, Technology and Research, Singapore 138648, Singapore
| | - Rong Li
- Department of Cell Biology, Johns Hopkins University School of Medicine, Baltimore, MD 21205
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36
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SENP1-modulated sumoylation regulates retinoblastoma protein (RB) and Lamin A/C interaction and stabilization. Oncogene 2016; 35:6429-6438. [PMID: 27270425 DOI: 10.1038/onc.2016.177] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2015] [Revised: 02/03/2016] [Accepted: 04/03/2016] [Indexed: 12/13/2022]
Abstract
The retinoblastoma tumor suppressor protein (RB) plays a critical role in cell proliferation and differentiation and its inactivation is a frequent underlying factor in tumorigenesis. While the regulation of RB function by phosphorylation is well studied, proteasome-mediated RB protein degradation is emerging as an important regulatory mechanism. Although our understanding of RB turnover is currently limited, there is evidence that the nuclear lamina filament protein Lamin A/C protects RB from proteasomal degradation. Here we show that SUMO1 conjugation of RB and Lamin A/C is modulated by the SUMO protease SENP1 and that sumoylation of both proteins is required for their interaction. Importantly, this SUMO1-dependent complex protects both RB and Lamin A/C from proteasomal turnover.
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37
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Meng F, Qian J, Yue H, Li X, Xue K. SUMOylation of Rb enhances its binding with CDK2 and phosphorylation at early G1 phase. Cell Cycle 2016; 15:1724-32. [PMID: 27163259 PMCID: PMC4957593 DOI: 10.1080/15384101.2016.1182267] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Retinoblastoma protein (Rb) is a prototypical tumor suppressor that is vital to the negative regulation of the cell cycle and tumor progression. Hypo-phosphorylated Rb is associated with G0/G1 arrest by suppressing E2F transcription factor activity, whereas Rb hyper-phosphorylation allows E2F release and cell cycle progression from G0/G1 to S phase. However, the factors that regulate cyclin-dependent protein kinase (CDK)-dependent hyper-phosphorylation of Rb during the cell cycle remain obscure. In this study, we show that throughout the cell cycle, Rb is specifically small ubiquitin-like modifier (SUMO)ylated at early G1 phase. SUMOylation of Rb stimulates its phosphorylation level by recruiting a SUMO-interaction motif (SIM)-containing kinase CDK2, leading to Rb hyper-phosphorylation and E2F-1 release. In contrast, a SUMO-deficient Rb mutant results in reduced SUMOylation and phosphorylation, weakened CDK2 binding, and attenuated E2F-1 sequestration. Furthermore, we reveal that Rb SUMOylation is required for cell proliferation. Therefore, our study describes a novel mechanism that regulates Rb phosphorylation during cell cycle progression.
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Affiliation(s)
- Fengxi Meng
- a Department of Ophthalmology , Eye and ENT Hospital of Fudan University , Shanghai , China.,b Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University , Shanghai , China
| | - Jiang Qian
- a Department of Ophthalmology , Eye and ENT Hospital of Fudan University , Shanghai , China.,b Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University , Shanghai , China
| | - Han Yue
- a Department of Ophthalmology , Eye and ENT Hospital of Fudan University , Shanghai , China.,b Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University , Shanghai , China
| | - Xiaofeng Li
- a Department of Ophthalmology , Eye and ENT Hospital of Fudan University , Shanghai , China.,b Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University , Shanghai , China
| | - Kang Xue
- a Department of Ophthalmology , Eye and ENT Hospital of Fudan University , Shanghai , China.,b Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University , Shanghai , China
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Kohno S, Kitajima S, Sasaki N, Takahashi C. Retinoblastoma tumor suppressor functions shared by stem cell and cancer cell strategies. World J Stem Cells 2016; 8:170-84. [PMID: 27114748 PMCID: PMC4835675 DOI: 10.4252/wjsc.v8.i4.170] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Revised: 12/30/2015] [Accepted: 02/14/2016] [Indexed: 02/06/2023] Open
Abstract
Carcinogenic transformation of somatic cells resembles nuclear reprogramming toward the generation of pluripotent stem cells. These events share eternal escape from cellular senescence, continuous self-renewal in limited but certain population of cells, and refractoriness to terminal differentiation while maintaining the potential to differentiate into cells of one or multiple lineages. As represented by several oncogenes those appeared to be first keys to pluripotency, carcinogenesis and nuclear reprogramming seem to share a number of core mechanisms. The retinoblastoma tumor suppressor product retinoblastoma (RB) seems to be critically involved in both events in highly complicated manners. However, disentangling such complicated interactions has enabled us to better understand how stem cell strategies are shared by cancer cells. This review covers recent findings on RB functions related to stem cells and stem cell-like behaviors of cancer cells.
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Affiliation(s)
- Susumu Kohno
- Susumu Kohno, Chiaki Takahashi, Division of Oncology and Molecular Biology, Cancer Research Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Shunsuke Kitajima
- Susumu Kohno, Chiaki Takahashi, Division of Oncology and Molecular Biology, Cancer Research Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Nobunari Sasaki
- Susumu Kohno, Chiaki Takahashi, Division of Oncology and Molecular Biology, Cancer Research Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
| | - Chiaki Takahashi
- Susumu Kohno, Chiaki Takahashi, Division of Oncology and Molecular Biology, Cancer Research Institute, Kanazawa University, Kanazawa, Ishikawa 920-1192, Japan
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Ouzounoglou E, Dionysiou D, Stamatakos GS. Differentiation resistance through altered retinoblastoma protein function in acute lymphoblastic leukemia: in silico modeling of the deregulations in the G1/S restriction point pathway. BMC SYSTEMS BIOLOGY 2016; 10:23. [PMID: 26932523 PMCID: PMC4774111 DOI: 10.1186/s12918-016-0264-5] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Accepted: 01/31/2016] [Indexed: 12/13/2022]
Abstract
BACKGROUND As in many cancer types, the G1/S restriction point (RP) is deregulated in Acute Lymphoblastic Leukemia (ALL). Hyper-phosphorylated retinoblastoma protein (hyper-pRb) is found in high levels in ALL cells. Nevertheless, the ALL lymphocyte proliferation rate for the average patient is surprisingly low compared to its normal counterpart of the same maturation level. Additionally, as stated in literature, ALL cells possibly reside at or beyond the RP which is located in the late-G1 phase. This state may favor their differentiation resistant phenotype. A major phenomenon contributing to this fact is thought to be the observed limited redundancy in the phosphorylation of retinoblastoma protein (pRb) by the various Cyclin Dependent Kinases (Cdks). The latter may result in partial loss of pRb functions despite hyper-phosphorylation. RESULTS To test this hypothesis, an in silico model aiming at simulating the biochemical regulation of the RP in ALL is introduced. By exploiting experimental findings derived from leukemic cells and following a semi-quantitative calibration procedure, the model has been shown to satisfactorily reproduce such a behavior for the RP pathway. At the same time, the calibrated model has been proved to be in agreement with the observed variation in the ALL cell cycle duration. CONCLUSIONS The proposed model aims to contribute to a better understanding of the complex phenomena governing the leukemic cell cycle. At the same time it constitutes a significant first step in the creation of a personalized proliferation rate predictor that can be used in the context of multiscale cancer modeling. Such an approach is expected to play an important role in the refinement and the advancement of mechanistic modeling of ALL in the context of the emergent and promising scientific domains of In Silico Oncology and more generally In Silico Medicine.
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Affiliation(s)
- Eleftherios Ouzounoglou
- In Silico Oncology and In Silico Medicine Group, Laboratory of Microwaves and Fiber Optics, Institute of Communication and Computer Systems, School of Electrical and Computer Engineering, National Technical University of Athens, 9 Iroon Polytechniou, Zografou, 15780, Athens, Greece.
| | - Dimitra Dionysiou
- In Silico Oncology and In Silico Medicine Group, Laboratory of Microwaves and Fiber Optics, Institute of Communication and Computer Systems, School of Electrical and Computer Engineering, National Technical University of Athens, 9 Iroon Polytechniou, Zografou, 15780, Athens, Greece.
| | - Georgios S Stamatakos
- In Silico Oncology and In Silico Medicine Group, Laboratory of Microwaves and Fiber Optics, Institute of Communication and Computer Systems, School of Electrical and Computer Engineering, National Technical University of Athens, 9 Iroon Polytechniou, Zografou, 15780, Athens, Greece.
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Montazeri H, Bouzari S, Azadmanesh K, Ostad SN, Ghahremani MH. Overexpression of Cyclin E and its Low Molecular Weight Isoforms Cooperate with Loss of p53 in Promoting Oncogenic Properties of MCF-7 Breast Cancer Cells. Asian Pac J Cancer Prev 2015; 16:7575-82. [DOI: 10.7314/apjcp.2015.16.17.7575] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
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Estève PO, Zhang G, Ponnaluri VKC, Deepti K, Chin HG, Dai N, Sagum C, Black K, Corrêa IR, Bedford MT, Cheng X, Pradhan S. Binding of 14-3-3 reader proteins to phosphorylated DNMT1 facilitates aberrant DNA methylation and gene expression. Nucleic Acids Res 2015; 44:1642-56. [PMID: 26553800 PMCID: PMC4770214 DOI: 10.1093/nar/gkv1162] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 10/21/2015] [Indexed: 11/15/2022] Open
Abstract
Mammalian DNA (cytosine-5) methyltransferase 1 (DNMT1) is essential for maintenance methylation. Phosphorylation of Ser143 (pSer143) stabilizes DNMT1 during DNA replication. Here, we show 14-3-3 is a reader protein of DNMT1pSer143. In mammalian cells 14-3-3 colocalizes and binds DNMT1pSer143 post-DNA replication. The level of DNMT1pSer143 increased with overexpression of 14-3-3 and decreased by its depletion. Binding of 14-3-3 proteins with DNMT1pSer143 resulted in inhibition of DNA methylation activity in vitro. In addition, overexpression of 14-3-3 in NIH3T3 cells led to decrease in DNMT1 specific activity resulting in hypomethylation of the genome that was rescued by transfection of DNMT1. Genes representing cell migration, mobility, proliferation and focal adhesion pathway were hypomethylated and overexpressed. Furthermore, overexpression of 14-3-3 also resulted in enhanced cell invasion. Analysis of TCGA breast cancer patient data showed significant correlation for DNA hypomethylation and reduced patient survival with increased 14-3-3 expressions. Therefore, we suggest that 14-3-3 is a crucial reader of DNMT1pSer143 that regulates DNA methylation and altered gene expression that contributes to cell invasion.
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Affiliation(s)
| | - Guoqiang Zhang
- New England Biolabs Inc, 240 County Road, Ipswich, MA 01938, USA
| | | | | | - Hang Gyeong Chin
- New England Biolabs Inc, 240 County Road, Ipswich, MA 01938, USA
| | - Nan Dai
- New England Biolabs Inc, 240 County Road, Ipswich, MA 01938, USA
| | - Cari Sagum
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX 78957, USA
| | - Karynne Black
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX 78957, USA
| | - Ivan R Corrêa
- New England Biolabs Inc, 240 County Road, Ipswich, MA 01938, USA
| | - Mark T Bedford
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Smithville, TX 78957, USA
| | - Xiaodong Cheng
- Department of Biochemistry, Emory University School of Medicine, Atlanta, GA 30322, USA
| | - Sriharsa Pradhan
- New England Biolabs Inc, 240 County Road, Ipswich, MA 01938, USA
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Tiwari S, Roel C, Wills R, Casinelli G, Tanwir M, Takane KK, Fiaschi-Taesch NM. Early and Late G1/S Cyclins and Cdks Act Complementarily to Enhance Authentic Human β-Cell Proliferation and Expansion. Diabetes 2015; 64:3485-98. [PMID: 26159177 PMCID: PMC4876788 DOI: 10.2337/db14-1885] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2014] [Accepted: 06/20/2015] [Indexed: 12/20/2022]
Abstract
β-Cell regeneration is a key goal of diabetes research. Progression through the cell cycle is associated with retinoblastoma protein (pRb) inactivation via sequential phosphorylation by the "early" cyclins and cyclin-dependent kinases (cdks) (d-cyclins cdk4/6) and the "late" cyclins and cdks (cyclin A/E and cdk1/2). In β-cells, activation of either early or late G1/S cyclins and/or cdks is an efficient approach to induce cycle entry, but it is unknown whether the combined expression of early and late cyclins and cdks might have synergistic or additive effects. Thus, we explored whether a combination of both early and late cyclins and cdks might more effectively drive human β-cell cell cycle entry than either group alone. We also sought to determine whether authentic replication with the expansion of adult human β-cells could be demonstrated. Late cyclins and cdks do not traffic in response to the induction of replication by early cyclins and cdks in human β-cells but are capable of nuclear translocation when overexpressed. Early plus late cyclins and cdks, acting via pRb phosphorylation on distinct residues, complementarily induce greater proliferation in human β-cells than either group alone. Importantly, the combination of early and late cyclins and cdks clearly increased human β-cell numbers in vitro. These findings provide additional insight into human β-cell expansion. They also provide a novel tool for assessing β-cell expansion in vitro.
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Affiliation(s)
- Shiwani Tiwari
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Chris Roel
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Rachel Wills
- Division of Endocrinology and Metabolism, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Gabriella Casinelli
- Division of Endocrinology and Metabolism, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Mansoor Tanwir
- Division of Endocrinology and Metabolism, University of Pittsburgh School of Medicine, Pittsburgh, PA
| | - Karen K Takane
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY
| | - Nathalie M Fiaschi-Taesch
- Diabetes, Obesity and Metabolism Institute, Icahn School of Medicine at Mount Sinai, New York, NY Division of Endocrinology and Metabolism, University of Pittsburgh School of Medicine, Pittsburgh, PA
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Kurimchak A, Graña X. PP2A: more than a reset switch to activate pRB proteins during the cell cycle and in response to signaling cues. Cell Cycle 2015; 14:18-30. [PMID: 25483052 PMCID: PMC4612414 DOI: 10.4161/15384101.2014.985069] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
In their active hypophosphorylated state, members of the retinoblastoma family of pocket proteins negatively regulate cell cycle progression at least in part by repressing expression of E2F-dependent genes. Mitogen-dependent activation of G1 and G1/S Cyclin Dependent Kinases (CDKs) results in coordinated hyperphosphorylation and inactivation of these proteins, which no longer bind and repress E2Fs. S and G2/M CDKs maintain pocket protein hyperphosphorylated through the end of mitosis. The inactivating action of inducible CDKs is opposed by the Ser/Thr protein phosphatases PP2A and PP1. Various trimeric PP2A holoenzymes have been implicated in dephosphorylation of pocket proteins in response to specific cellular signals and stresses or as part of an equilibrium with CDKs throughout the cell cycle. PP1 has specifically been implicated in dephosphorylation of pRB in late mitosis and early G1. This review is particularly focused on the emerging role of PP2A as a major hub for integration of growth suppressor signals that require rapid inactivation of pocket proteins. Of note, activation of particular PP2A holoenzymes triggers differential activation of pocket proteins in the presence of active CDKs.
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Affiliation(s)
- Alison Kurimchak
- a Fels Institute for Cancer Research and Molecular Biology and Department of Biochemistry; Temple University School of Medicine ; Philadelphia , PA USA
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Teo T, Lam F, Yu M, Yang Y, Basnet SKC, Albrecht H, Sykes MJ, Wang S. Pharmacologic Inhibition of MNKs in Acute Myeloid Leukemia. Mol Pharmacol 2015; 88:380-9. [DOI: 10.1124/mol.115.098012] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 06/04/2015] [Indexed: 01/07/2023] Open
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Hu X, Luo P, Peng X, Song T, Zhou Y, Wei H, Peng J, Jiang S. Molecular cloning, expression pattern analysis of porcine Rb1 gene and its regulatory roles during primary dedifferentiated fat cells adipogenic differentiation. Gen Comp Endocrinol 2015; 214:77-86. [PMID: 25626122 DOI: 10.1016/j.ygcen.2015.01.016] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/30/2014] [Revised: 01/13/2015] [Accepted: 01/19/2015] [Indexed: 11/19/2022]
Abstract
Adipocytes are the main constituent of adipose tissue and are considered to be a corner stone in the homeostatic control of whole body metabolism. Recent reports evidenced that retinoblastoma 1 (Rb1) gene plays an important role in fat development and adipogenesis in mice. Here, we cloned the partial cDNA sequences of the porcine Rb1 gene which contains the complete coding sequences (CDS) of 2820bp encoding a protein of 939 amino acids. Bioinformatic analysis revealed that the CDS of porcine Rb1 was highly identical with those of cattle, human and mice. The porcine Rb1 has three typical conserved structural domains, including Rb-A pocket domain, CYCLIN domain and C-terminus domain, and the phylogenetic tree indicates a closer genetic relationship with cattle and human. Tissue distribution analysis showed that Rb1 expression appeared to be ubiquitously in various tissues, being higher in heart, liver, muscle, and stomach. Furthermore, significant downregulation of Rb1 was found at the initial stage of dedifferentiated fat (DFAT) cells adipogenic differentiation. With the knockdown of the Rb1 expression by siRNA, the number of DFAT cells recruited to white rather than brown adipogenesis was promoted, and mRNA levels of adipogenic markers, such as PPARγ, aP2, LPL and adiponectin and protein expression of PPARγ and adiponectin were increased after hormone stimulation. The underlying mechanisms may be that knockdown of Rb1 promotes the mitotic clonal expansion and PPARγ expression by derepressing the transcriptional activity of E2F so as to facilitate the first steps of adipogenesis. In summary, we cloned and characterized an important negative regulator in adipogenic commitment of porcine DFAT cells.
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Affiliation(s)
- Xiaoming Hu
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, People's Republic of China
| | - Pei Luo
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Xuewu Peng
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Tongxing Song
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Yuanfei Zhou
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Hongkui Wei
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China
| | - Jian Peng
- Department of Animal Nutrition and Feed Science, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, People's Republic of China.
| | - Siwen Jiang
- Key Laboratory of Animal Genetics, Breeding and Reproduction of Ministry of Education, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; Key Laboratory of Swine Genetics and Breeding of Agricultural Ministry, College of Animal Science and Technology, Huazhong Agricultural University, Wuhan 430070, People's Republic of China; The Cooperative Innovation Center for Sustainable Pig Production, Wuhan 430070, People's Republic of China.
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The retinoblastoma tumor suppressor promotes efficient human cytomegalovirus lytic replication. J Virol 2015; 89:5012-21. [PMID: 25694602 DOI: 10.1128/jvi.00175-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2015] [Accepted: 02/13/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED The retinoblastoma (Rb) tumor suppressor controls cell cycle, DNA damage, apoptotic, and metabolic pathways. DNA tumor virus oncoproteins reduce Rb function by either inducing Rb degradation or physically disrupting complexes between Rb and its myriad binding proteins. Human cytomegalovirus (HCMV), a betaherpesvirus being investigated for potential roles in human cancers, encodes multiple lytic-phase proteins that inactivate Rb in distinct ways, leading to the hypothesis that reduced Rb levels and/or activity would benefit HCMV lytic infection. Paradoxically, we found that Rb knockdown prior to infection, whether transient or constitutive, impaired HCMV lytic infection at multiple stages, notably viral DNA replication, late protein expression, and infectious virion production. The existence of differentially modified forms of Rb, the temporally and functionally distinct means by which HCMV proteins interact with Rb, and the necessity of Rb for efficient HCMV lytic replication combine to highlight the complex relationship between the virus and this critical tumor suppressor. IMPORTANCE Initial work examining viral protein modulation of cell cycle progression and oncogenic transformation revealed that these proteins inactivated the function of cellular tumor suppressor proteins. However, subsequent work, including experiments described here using human cytomegalovirus, demonstrate a more nuanced interaction that includes the necessity of cellular tumor suppressors for efficient viral replication. Understanding the positive impacts that cellular tumor suppressors have on viral infections may reveal new activities of these well-studied yet incompletely understood proteins. The basis for oncolytic viral therapy is the selective replication of viruses in transformed cells in which tumor suppressor function may be compromised. Understanding how tumor suppressors support viral infections may allow for the generation of modified oncolytic viruses with greater selective tumor cell replication and killing.
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PRMT4-mediated arginine methylation negatively regulates retinoblastoma tumor suppressor protein and promotes E2F-1 dissociation. Mol Cell Biol 2014; 35:238-48. [PMID: 25348716 DOI: 10.1128/mcb.00945-14] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
The retinoblastoma protein (pRb/p105) tumor suppressor plays a pivotal role in cell cycle regulation by blockage of the G1-to-S-phase transition. pRb tumor suppressor activity is governed by a variety of posttranslational modifications, most notably phosphorylation by cyclin-dependent kinase (Cdk) complexes. Here we report a novel regulation of pRb through protein arginine methyltransferase 4 (PRMT4)-mediated arginine methylation, which parallels phosphorylation. PRMT4 specifically methylates pRb at the pRb C-terminal domain (pRb C(term)) on arginine (R) residues R775, R787, and R798 in vitro and R787 in vivo. Arginine methylation is important for efficient pRb C(term) phosphorylation, as manifested by the reduced phosphorylation of a methylation-impaired mutant, pRb (R3K). A methylmimetic form of pRb, pRb (R3F), disrupts the formation of the E2F-1/DP1-pRb complex in cells as well as in an isolated system. Finally, studies using a Gal4-E2F-1 reporter system show that pRb (R3F) expression reduces the ability of pRb to repress E2F-1 transcriptional activation, while pRb (R3K) expression further represses E2F-1 transcriptional activation relative to that for cells expressing wild-type pRb. Together, our results suggest that arginine methylation negatively regulates the tumor suppressor function of pRb during cell cycle control, in part by creating a better substrate for Cdk complex phosphorylation and disrupting the interaction of pRb with E2F-1.
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Cho HJ, Park JHY. Kaempferol Induces Cell Cycle Arrest in HT-29 Human Colon Cancer Cells. J Cancer Prev 2014; 18:257-63. [PMID: 25337553 PMCID: PMC4189462 DOI: 10.15430/jcp.2013.18.3.257] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Revised: 09/08/2013] [Accepted: 09/09/2013] [Indexed: 01/06/2023] Open
Abstract
Background: A greater intake of vegetables and fruits has been linked to a reduced incidence of colon cancer. Flavonoids are polyphenolic compounds which are broadly distributed in fruits and vegetables and display a remarkable spectrum of physiological activities, including anti-carcinogenic effects. The objective of this study was to determine the mechanisms by which kaempferol, a flavonol present in tea, apples, strawberries, and beans, inhibits the growth of HT-29 human colon cancer cells. Methods: To examine the effects of kaempferol on cell cycle progression in HT-29 cells, cells were treated with various concentrations (0–60 μmol/L) of kaempferol. Cell proliferation and DNA synthesis were evaluated by MTT assay and [3H]thymidine incorporation assay, respectively. Fluorescence-activated cell sorting analyses were conducted to calculate cell cycle phase distribution. Western blot analyses and in vitro kinase assays were used to estimate the expression of proteins involved in the regulation of cell cycle progression and the activity of cyclin-dependent kinase (CDK)s, respectively. Results: Kaempferol decreased viable cell numbers and [3H]thymidine incorporation into DNA of HT-29 cells in a dose-dependent manner. Kaempferol induced G1 cell cycle arrest within 6 h and G2/M arrest at 12 h. Kaempferol inhibited the activity of CDK2 and CDK4 as well as the protein expression of CDK2, CDK4, cyclins D1, cyclin E, and cyclin A, and suppressed the phosphorylation of retinoblastoma protein. Additionally, kaempferol decreased the levels of Cdc25C, Cdc2, and cyclin B1 proteins, as well as the activity of Cdc2. Conclusions: The present results indicate that kaempferol induces G1 and G2/M cell cycle arrest by inhibiting the activity of CDK2, CDK4, and Cdc2. The induction of cell cycle arrest may be one of the mechanisms by which kaempferol exerts anti-carcinogenic effects in colon cancer cells.
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Affiliation(s)
- Han Jin Cho
- Department of Food and Nutrition, Hallym University, Chuncheon, Korea
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Pernicová Z, Slabáková E, Fedr R, Šimečková Š, Jaroš J, Suchánková T, Bouchal J, Kharaishvili G, Král M, Kozubík A, Souček K. The role of high cell density in the promotion of neuroendocrine transdifferentiation of prostate cancer cells. Mol Cancer 2014; 13:113. [PMID: 24884804 PMCID: PMC4229954 DOI: 10.1186/1476-4598-13-113] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Accepted: 05/13/2014] [Indexed: 11/13/2022] Open
Abstract
Background Tumor heterogeneity and the plasticity of cancer cells present challenges for effective clinical diagnosis and therapy. Such challenges are epitomized by neuroendocrine transdifferentiation (NED) and the emergence of neuroendocrine-like cancer cells in prostate tumors. This phenomenon frequently arises from androgen-depleted prostate adenocarcinoma and is associated with the development of castration-resistant prostate cancer and poor prognosis. Results In this study, we showed that NED was evoked in both androgen receptor (AR)-positive and AR-negative prostate epithelial cell lines by growing the cells to a high density. Androgen depletion and high-density cultivation were both associated with cell cycle arrest and deregulated expression of several cell cycle regulators, such as p27Kip1, members of the cyclin D protein family, and Cdk2. Dual inhibition of Cdk1 and Cdk2 using pharmacological inhibitor or RNAi led to modulation of the cell cycle and promotion of NED. We further demonstrated that the cyclic adenosine 3′, 5′-monophosphate (cAMP)-mediated pathway is activated in the high-density conditions. Importantly, inhibition of cAMP signaling using a specific inhibitor of adenylate cyclase, MDL-12330A, abolished the promotion of NED by high cell density. Conclusions Taken together, our results imply a new relationship between cell cycle attenuation and promotion of NED and suggest high cell density as a trigger for cAMP signaling that can mediate reversible NED in prostate cancer cells.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | - Karel Souček
- Department of Cytokinetics, Institute of Biophysics, Academy of Sciences of the Czech Republic, v,v,i, Královopolská 135, CZ-612 65 Brno, Czech Republic.
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Milewska M, Kolch W. Mig-6 participates in the regulation of cell senescence and retinoblastoma protein phosphorylation. Cell Signal 2014; 26:1870-7. [PMID: 24815188 DOI: 10.1016/j.cellsig.2014.05.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2014] [Revised: 04/30/2014] [Accepted: 05/02/2014] [Indexed: 12/13/2022]
Abstract
Mitogen-inducible gene-6 (Mig-6) is a cytosolic multiadaptor protein that is best known for its role as a negative feedback regulator of epidermal growth factor receptor (EGFR) mediated signalling. Alternative roles of Mig-6 are becoming increasingly recognised. Consistently with this, Mig-6 was demonstrated to be involved in a broad spectrum of cellular events including tumour suppression which may include the induction of cellular senescence. Here, we investigated the mechanisms of Mig-6 induced premature cell senescence. Endogenous Mig-6 is poorly expressed in young fibroblasts, whilst its expression rises in cells presenting with typical features of senescence. Overexpression of Mig-6 is sufficient to trigger premature cellular senescence of early passage diploid lung fibroblasts (WI-38). Interestingly, Mig-6 overexpression reduced retinoblastoma protein (pRb) phosphorylation at the inactivating Ser249/Thr252 sites. We also found that phosphorylation of these sites in pRb is increased in the presence of the B-Raf V600E oncogenic mutation. We further show that Mig-6 overexpression reduces B-Raf V600E mediated pRb inactivation and preserves pRb function.
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Affiliation(s)
- Malgorzata Milewska
- Systems Biology Ireland, University College Dublin, Belfield, Dublin 4, Ireland.
| | - Walter Kolch
- Systems Biology Ireland, University College Dublin, Belfield, Dublin 4, Ireland; Conway Institute of Biomolecular & Biomedical Research, University College Dublin, Belfield, Dublin 4, Ireland; School of Medicine and Medical Science, University College Dublin, Belfield, Dublin 4, Ireland.
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